• Korean Journal of Ichthyology
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• v.26 no.1
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• pp.17-24
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• 2014

The egg development and early life history of Acheilognathus majusculus which is Korean endemic species from Yeong river were observed under the controlled water temperature, $18.0{\pm}1.0^{\circ}C$. Fertilized eggs are opaque yellow in color and round oval shaped measuring 2.12 (2.08~2.18) mm in length and 1.86 (1.80~1.98) mm in breadth. The number of eggs averaged 72 (40~112) per an oviposition. The eggs of this species began to hatch about forty three hours after insemination and the total length of larvae was 4.23 mm mean. S form moving of larvae were not observed during larval development. The larvae reached at the heterotrophic stage about twenty-five days after hatching. It is estimated that the larvae was comming out from freshwater bivalve since that time in nature. A. majusculus was grew up to be adult stage enough which can be join to new production for three hundred days after hatching with over 67.8 mm in total length.

• Korean Journal of Ichthyology
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• v.21 no.3
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• pp.141-148
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• 2009

Sex differentiation and gonad development were investigated in a marine medaka species, Oryzias dancena (Beloniformes; Teleostei). The average time to hatch was 11 days post-fertilization (dpf) at $25^{\circ}C$. Primordial germ cell (PGC) was first observed at 5 dpf and migrated to presumptive gonadal area between the gut and pronephric duct at 9 dpf. Male and female gonads were morphologically differentiated at 12 days post-hatching (dph). Early oocytes at perinucleolus stage as well as the formation of spermatid and efferent duct were observed at 28 dph. At 6 weeks of age, the ovary exhibited yolk granulation in many oocytes, while testis possessed a considerable number of spermatogonia and spermatids. The first ovulation was observed in 9-week-old females, and at the same age, males contained fully-matured spermatozoa. Data obtained in this study indicate that the gonad differentiation of O. dancena is the typical type of differentiated gonochorism.

• The Korean Journal of Ecology
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• v.26 no.1
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• pp.1-4
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• 2003

In diurnal activity of the black-crowned night herons on breeding season, activity budget was that male were standing(29.5%), preening(21.5%), comfort(10.9%), and female were resting(26.3%), repairing (18.4%), preening(15.3%) in sequence. Activity budget was high significant between male and female(p<0.01). In case of activity-time budget sequence, male was standing(38.7%), locomotion(33.8%), preening(11.5%), and female was resting(55.4%), standing(18.4%), preening(9.4%). Therefore, activity-time budget was significantly different in male and female(p<0.01).

• Journal of Aquaculture
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• v.11 no.4
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• pp.521-528
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• 1998

The influence of starvation on survival, growth and feeding incidence of larval tiger puffer Takifugu rubripes was investigated for 16 days after let them hatched at the temperature of 16.5~18.5${\circ}C$. The effect by delayed initial feeding on larvace was also studied. Almost all larvae began to be fed from the stage of yolk absorption about 5 days after hatching, in which rearing trials revealed that their survival and growth were influenced by food availability. Survival of unfed larvae, which stated to decrease drastically since the oil globule was exhausted about 9 days after hatching, dropped to 50% and 0% respectively on the 11.5th and 16th day. the difference of growth between fed and unfed larvae came into sight on about 5th day after hatching when the initial feeding was started, and had reduced in proportion to the length of starvation period. The condition factors for the unfed larvae were lower than thost of the fed. Of the larvae which had starved less than 5 days, more than 80% could consume food upon feeding. No fish had the ability in having food after 10 days. It appeared that the turning point of recover for the starving larvae came on 7th or 8th day. Their taking-food ability seemed to be affected by the change in swimming activity which depended on the duration of starvation. For the seed production of tiger puffer, therefore, feeding should be initiated as soon as possible, so as to enhance the production and survival of healthy seeds.

• Korean Journal of Ichthyology
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• v.23 no.2
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• pp.150-157
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• 2011

In this study we described reproduction study of Korean endemic species, Acheilognathus koreensis and three other acheilognathinae species A. signifer, Rhodeus pseudosericeus, and R. uyekii. Morphology of egg shape and larvae just hatched is unique by the species respectively. There is no interrelation factor between size of female and number of spawned eggs per one time. Minium water temperature for spawning of A. koreensis was observed in $13.0^{\circ}C$ having low hatching rate with 43.5 percent. The egg of A. koreensis began to hatch approximately 79 hours after insemination. As higher as water temperature until $22.0^{\circ}C$ hatching elapsed time for developing eggs of A. koreensis and three species in this study was shortened. A. koreensis was grew up to be a adult enough which can be join to new production for three hundred days after hatching with 52.4 mm in total length. This reproduction study will be applied to preservation of Korean endemic fresh water fishes basically.

• Korean Journal of Ichthyology
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• v.34 no.1
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• pp.16-24
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• 2022

The eggs development and early life history of Sarcocheilichthys variegatus wakiyae was investigated. The adult fishes were collected in Yeongsangang River, Damyang-gun, Jeollanam-do, Korea, and their spawning inducement was carried by sex maturation hormone (Ovaprim) injections. Spawning amount was mean 31±3.5 Mature eggs were cicular in shape and mean 2.40±0.05 mm in diameter. Hatching period of the embryo was 230 to 240 hours after fertilization under water temperature of 22℃. The newly hatched larvae were 10.7±0.19 mm in total length (TL). 3 days after hatching, postlarvae was measured 12.0±0.13 mm in TL and the tip of the caudal fin was bent at 45°. 11 days after hatching, it was measured 14.6±0.13 mm in TL, and transferred to juvenile as the number of fins (iii7 dorsal fin, iii6 anal fin, i7 ventral fins) reached a constant number of each part.

• Korean Journal of Ichthyology
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• v.18 no.3
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• pp.266-272
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• 2006

The egg development and early life history of Korean endemic bitterling Rhodeus pseudosericeus were observed under the controlled water temperature, $17.0{\pm}0.5^{\circ}C$. Fertilized eggs are opaque yellow in color, measuring 2.9~3.1 mm in length and 1.6~1.9 mm in breadth. The eggs of this species began to hatch about seventy hours after insemination and the range of total length of larvae were 3.2~3.4 mm. The larvae reached at the heterotrophic stage about twenty-five days after hatching. R. pseudosericeus had a pair of wing-shaped yolk projection during the prelarval stage that is a common character of the genus Rhodeus.

• The Korean Journal of Pesticide Science
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• v.14 no.2
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• pp.157-163
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• 2010

This study was performed to investigate the hatching rate and eggs period until hatching in the laboratory against lantern fly, Lycorma delicatula eggs with different collecting date of eggs, and the susceptibility of 26 insecticides to the eggs, 1st and 2nd nymphs of Lycorma delicatula. The eggs of L. delicatula were increased the hatching rates as passed collecting date of eggs, and shorten in eggs period until hatching. By screening the susceptibility of 26 insecticides to the eggs, 1st, and 2nd nymphs, chlorpyrifos (312.5 ppm) showed the perfect inhibition effect of hatching against the eggs, however, the other insecticides did not show that effect. According to the collecting date of eggs, chlorpyrifos bioassayed the inecticidal effect with different concentration (625 ppm at double conc., 312.5 ppm at recommended conc., and 156.3 ppm at half conc.). The eggs collected from Apr. 20th 2010, were showed the inhibition effect of hatching over 94.5%, but the eggs collected from May 10th, 2010 were showed the inhibition effect of hatching as 86.7, 71.1, and 47.1%, respectively. However, hatched eggs were all killed perfectly within 24 hours. At recommended and half concentrations, the eggs collected from 15, May, are decreased the effect as 48.6%, 53.7%, respectively, and the mortality of eggs hatched also decreased as 61.0 and 22.0%, respectively, however, double concentrations did not show the changes. From the above results, it will be anticipate to show the higher mortality against the eggs of L. delicatula when treated chlorpyrifos until late-April.

• Korean Journal of Ichthyology
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• v.12 no.3
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• pp.208-214
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• 2000

The egg development and morphological changes of larvae of the file fish, Thamnaconus modestus(Gunther), was investigated by artificial insemination. The fertilized egg was spherical in shape, colorless and adhesive with 0.63~0.67mm in diameter and yolk had 20~30 oil globules of various size (0.04~0.16 mm in diameter). The hatching occured at 53 hours after fertilization in $21.0\sim23.0^{\circ}C$ of water temperature. Hatched larvae measured 2.07~2.20 mm in total length with 5~6+17~18=22~24 myotomes. The 3~4 days after hatching larvae grew to the total length 2.62~2.77 mm, opened mouth and anus. The 5 days after hatching, total length of the larvae was 2.74~3.04 mm, the first dorsal fin was formed at the behind of head. After hatching 12~13 days larvae attained 3.78~3.99 mm in total length. This period formed rudimental dorsal fin and anal fin. Twenty days after hatching, larvae grew to 6.04~6.17mm in total length, at which time the dorsal, anal and caudal fin rays reached 19~20, 18~19 and 9~10, respectively.

• Food Science of Animal Resources
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• v.27 no.4
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• pp.401-408
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• 2007

This study examined the histochemical and physiological characteristics during Korean native Ogol chickens (KNOC) development. The body weight, Pectoralis major and soleus muscle weights, and muscle samples were taken at hatching as well as at 3, 5, and 15 weeks of age. The fiber characteristics of the Pectoralis major and soleus muscles from the KNOC at hatching to 15 weeks of age were determined, and the deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and protein concentrations were measured from the left Pectoralis major muscles. A greater increase in body and muscle weights was detected between hatching and 3 weeks of age than during any other period. Moreover, the cross sectional area (CSA) of the fibers, as well as the total concentration of DNA, RNA, and protein also showed a greater increase betweenhatching and 3 weeks of age than during any other period. The KNOC breed is a dual purpose breed, however, the it has lower body and muscle weights than commercial meat type chickens or layer type chickens. Moreover, the KNOC breed has a small muscle fiber CSA of and a low nucleic acid concentration.